Chemical Oxidation David Robinson, LSRP Synergy Environmental - - PowerPoint PPT Presentation

Rapid Treatment of Hydrocarbons Utilizing In Situ Chemical Oxidation

David Robinson, LSRP Synergy Environmental Cherry Hill, New Jersey

Site Overview

• Active retail petroleum site on NYS

Thruway

– Unleaded gas, diesel, kerosene

• Not practical to shut down service station
• 2006 – petroleum contamination

discovered near dispensers

– No groundwater quality investigation performed at that time – 2010 – 33 monitoring wells installed to determine groundwater quality

Geology

• Regional Geology

– Overburden soils consist of glacial till – Deeper strata bedrock

• Site Geology

– Silty/sand underlain by weathered shale – 5-10 ft drop in topography moving west to east across the site

Groundwater

• Generally flows southeast following soil

topography

• Depth to groundwater

– 3 feet below ground surface western portion of the property (near USTs) – 16 feet below ground surface eastern side

• f the property

– Perched groundwater exists up-gradient of pump island

Perched GW

Analytical Results

• Soil contamination from

12 feet below grade to 26 feet below grade

• High concentrations of

VOC gasoline constituents

• Groundwater above

NYSDEC cleanup levels extend throughout property

• GW source identified

downgradient of the pump island

Soil Groundwater Concentrationmax Concentrationmax (mg/kg) (mg/L) ethylbenzene 77 12 n-butylbenzene 4.6 0.65 isopropylbenzene 7.5 2.4 napthalene 29 3.5 n-propylbenzene 33 3.4 toluene 230 36 1,2,4-trimethylbenzene 210 20 1,3,5-trimethylbenzene 60 7.7 total xylenes 430 61 MTBE not analyzed 0.2 total SVOC <1.0 <1.0 Compound

Remedial Selection

• Excavation

– Active gas station and extent of contamination made excavation infeasible

• Biodegradation/MNA

– Based on soil/groundwater concentrations, NYSDEC would not considered

• In situ chemical oxidation - ozone

– Smallest treatment footprint – Effective – Short timeframe

Pilot Study

• 3 sparge points installed

– Upgradient, source area, down gradient – 2” id PVC risers with 3 feet of screen installed (installed to be used as monitoring wells later) – Subgrade conduit from well head to treatment trailer – ¼’ ozone compatible tubing snaked through conduit and sparge well – Packers used to seal wells and contain fugitive emission

Ozone System

• Self contained trailer system used for
• zone generation and sparge controls
• Ozone generated utilizing 2 L/min air

compressor, oxygen concentrator and 2.1 lb/day ozone generator

• Compressed air added to stream post-
• zone generator as makeup gas for

desired flow rates

Pilot Test

• Serial injection of ozone into each well

SP-1 SP-2 SP-3

• Dissolved oxygen measured

continuously at surrounding wells

• Groundwater sampling performed post
• zone treatment

Pilot Test

• SP-1(Source Area)

– Diffuser set at 25’ (GW @ 17 fbgs) – 6/L min flow 30 g/hr – 65 hours operation ~ 4.5 lbs O3

• SP-2 (Down Gradient)

– Diffuser set at 29’ (GW @ 16.5 fbgs) – 5/L min flow 27 g/hr – 145 hours operation ~ 8.6 lbs O3

Pilot Test

• SP-3 (Upgradient)

– Diffuser set at 21’ (GW @ 8 ft bgs) – 4/L min flow 22 g/hr – 87 hours operation 4.2 lbs O3

• Dissolved oxygen was sampled in

surrounding wells to determine radii of influence

Dissolved Oxygen Results

SP-1

Well Distance From Sparge Point (feet) Initial DO (mg/L) Final DO (mg/L) SP-1 0.99 15.6 MW-22 12 1.06 1.87 MW-35 19 0.46 1.56 SP-2 30 1.53 10.17 No Influence Seen in Wells > 40 feet

SP-2

Well Distance From Sparge Point (feet) Initial DO (mg/L) Final DO (mg/L) MW-26 0.4 9.5 11.8 MW-35 10 0.55 7.1 EW-1 26 0.67 2.9 No Influence Seen in Wells > 30 feet

SP-3

Well Distance From Sparge Point (feet) Initial DO (mg/L) Final DO (mg/L) MW-9 10 1.1 3.8 MW-34 16 0.8 2.2 No Influence Seen in Wells > 30 feet

Pilot Study Conclusion

• The radius of influence for ozone is 20-30

feet depending on location

• Concentrations of hydrocarbons in the source

area (SP-1) did not degrade and showed a transient increase

• Hydrocarbon concentrations upgradient/down

gradient decreased

• Ozone was delivered with enough pressure

and flow to treat the large contamination area from a single trailer

Full Scale Treatment

• Approximately 5,000 lbs of VOCs in subsurface
• Full scale treatment began in 2009
• System operated remotely through web-based

Remediation Operating System Equipment (ROSE)

• Groundwater monitoring performed quarterly

starting 2010

• Results have shown consistent decrease in total

VOC concentrations

• Anticipate operating system until 2014

Treatment Trailer